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Anterior ischemic optic neuropathy is the most frequent cause of sight loss in people over 50 years of age. Ischemia is a term meaning inadequate blood supply, and optic neuropathy means an abnormality to the optic nerve which supplies the eye. Anterior means at the front, so anterior ischemic optic neuropathy refers to damage to the front part of the optic nerve, caused by an insufficient blood supply. The disease normally affects only one eye at first, giving rise to symptoms of dull, blurred vision. Although the condition is not fully understood, and there is no effective treatment, it does not usually worsen over time.
The causes of anterior ischemic optic neuropathy are still being researched, but it is known that tiny blood vessels, called the posterior ciliary arteries, fail to supply enough blood to the optic nerve. This nerve carries information between the eye and the brain. It is possible that smokers and people with high blood pressure or diabetes may have an increased risk of developing this type of ischemic neuropathy. Some people with anterior ischemic optic neuropathy suffer from a condition which leads to the arteries becoming inflamed, known as arteritis.
Symptoms of anterior ischemic optic neuropathy include loss of vision, typically experienced slightly higher or lower than the central field of view. There is not usually any pain, unless the person has arteritis, in which case headaches, fever, weight loss, muscle aches, scalp and jaw pain may be experienced, together with other symptoms. Sight loss is generally more severe in people with the arteritic form of anterior ischemic optic neuropathy, and it is more common for the other eye to become involved.
Where the head of the optic nerve joins the retina, the tissue at the back of the eye that responds to light, it forms a blind spot known as the optic disc. In someone with anterior ischemic optic neuropathy, the optic disc appears swollen, and hemorrhages may be visible on its surface. Neuropathy is known to occur more frequently in people who have small optic discs, although the reason for this is not understood.
There is no effective treatment for anterior ischemic optic neuropathy, and once vision has been lost it can not be restored. For patients with arteritis, steroid treatment can help prevent sight loss from affecting the other eye and can decrease the effects of arteritis in other parts of the body. Many doctors recommend taking aspirin daily to prevent progression of ischemic optic neuropathy to the other eye, but there is currently no evidence to show that this is effective.